The present invention relates to a sheet aligning apparatus and an image forming system. Especially, the present invention relates to a sheet aligning apparatus which makes it possible to perform a sheet post processing efficiently and an image forming system equipped with the sheet aligning apparatus.
Conventionally, as an image forming system, a well known system is equipped with an image forming apparatus, such as a printer, a copying machine, and a composite machine, and a post processing apparatus which performs a post processing, such as a punching process, a folding process, a binding process, and so forth for to sheets on which images have been formed by the image forming apparatus.
A post processing section as a structural section of an image forming system is generally an apparatus which performs a shifting process, a punching process, a binding process, a folding process, a pasting bookbinding process, etc. for sheets on which images have been formed.
Moreover, for such a punching process section, a binding process section, a folding process section, and a pasting bookbinding process section, an aligning process section for aligning sheets as a pretreatment section of those processes is provided.
Generally, this aligning process section is provided in a post processing section, has a structure which comprises an inclined intermediate stacker and a movable regulating member provided in the both sides or one side of the intermediate stacker, and conducts an aligning process for sheets on a conveyance path to convey sheets to a binding process section or a folding process section. Namely, the aligning process section drops and slides sheets into the inclined intermediate stacker to align sheets in the conveying direction. In the stage where the preset number of sheets has been accumulated in the intermediate stacker, the aligning process section stops feeding sheets to the intermediate stacker, reciprocates a movable regulating member, and aligns sheets in the widthwise direction of the conveyance path. Thereafter, a post processing, such as a punching process, a binding process, a folding process, and a pasting bookbinding process, is performed for the aligned sheets.
Furthermore, in conventional post processing apparatuses, there is a post processing apparatus in which a sheet reversing conveying section called an intermediate conveyance unit and a sheet width regulating member to align sheets widthwise are provided before post processing. However, there is no post processing apparatus equipped with a sheet aligning section to align sheets in the sheet conveying direction in the sheet reversing conveying section. The conventional post processing apparatuses conduct sheet aligning just before performing post processing, such as a punching process, a binding process, and a folding process by regulating the leading end or back end of sheets in respective post process.
Therefore, since it is necessary to take time to align sheets in each post process, there is a problem that a sheet processing speed becomes low.
Moreover, conventional aligning process sections need to stop conveying a succeeding sheet during conducting post processing for preceding sheets. Therefore, since the sheet processing speed becomes low more, the conventional aligning process sections are not suited for the high speed performance of an image forming apparatus. As a result, there is a problem that the high speed performance of an image forming apparatus is not fully exhibited.
Furthermore, when performing an aligning process, since conveyance stop control is executed, the control method becomes complicated, and stability tends to be failed. Therefore, there is further a problem that a conveyance trouble such as a jam tends to occur easily.
In order to solve these problems, for example, Japanese Patent Unexamined Publication No. 2007-137536 discloses a technique to provide a sheet aligning apparatus in an intermediate conveyance unit so that a plurality of sheets are conveyed simultaneously and an aligning process for succeeding sheets can be performed at high speed even if preceding sheets are subjected to a post processing.
According to the technique disclosed by the above publication, a sheet storage section to store a plurality of inversed sheets is provided between an image forming apparatus and a post processing apparatus, the sheet storage section receives sheets by a stop member capable of shifting upward and downward, and conducts sorting and aligning succeeding sheets in the conveying direction by shifting the stop member.
FIG. 16 is a front side cross sectional view of an intermediate conveyance unit B which has the sheet storage section equipped with the sheet aligning device disclosed by the above publication.
Hereafter, the structure and operations of the sheet aligning apparatus by the use of the above intermediate conveyance unit B are explained as an conventional example with reference to FIG. 16.
In FIG. 16, the intermediate conveyance unit B is provided at the downstream side of an image forming apparatus main body A in the sheet conveying direction, and a post processing apparatus FS is arranged further at the downstream side of the intermediate conveyance unit B.
A sheet conveyance section of the intermediate conveyance unit B is constituted by a sheet conveying-in section (first conveying section) 11, a sheet storage section (second conveying section) 12, a sheet conveying-out section (third conveying section) 13, and a sheet reversing section (fourth conveying section) 14.
The sheet conveying-in section 11 is equipped with a sheet conveying-in conveyance path r11 which comprises conveying rollers R1 and R2 and a guide plate 111. In the sheet conveying-in section 11, sheets S discharged from a discharging section 5E of the image forming apparatus main body A are conveyed sequentially.
The sheet storage section 12 is equipped with two guide plates 121, a widthwise aligning section 122, a stop member 123, a lengthwise aligning member 124, a conveying-in drive roller R3, a conveying-out drive roller R4, and a sheet storage conveyance path r12.
The two guide plates 121 are arranged in parallel, and form the sheet storage conveyance path r12 therebetween.
The sheet storage conveyance path r12 is a conveying path for conveying in or conveying out sheets S for the sheet storage section 12.
Plural sheets S conveyed from the sheet conveying-in section 11 into the sheet storage section 12 are arranged on the stacked condition and stored in the sheet storage section 12. Then, the plural sheets S are aligned in the sheet conveying direction between the stop member 123 and the lengthwise aligning member 124, further aligned in the sheet width direction by the widthwise aligning member 122, and thereafter discharged upward.
The stop member 123 being stopping and waiting at an initial stop position P0 is shifted upward by a motor (not illustrated in the drawing) along the sheet storage conveyance path r12, and stopped at the first stop position P1 or the second stop position P2.
Namely, a preceding sheet S1 is conveyed in the sheet conveying-in direction from the sheet conveying-in section 11 into the sheet storage section 12, and the leading end of a preceding sheet S1 in the sheet conveying-in direction comes in contact with a stopping surface 123A of the stop member 123. Thereafter, the stop member 123 is shifted upward in the sheet conveying-out direction by a stop member shifting section (the above motor) so that the stop member 123 conveys the preceding sheet S1 inversely in the sheet conveying-out direction. Then, the back end of the preceding sheet becomes the inversed leading end of the preceding sheet in the sheet conveying-out direction by the inversely conveying, and when the inversed leading end (the back end) of the preceding sheet arrives at a middle point between the conveying-in drive roller R3 and the conveying-out drive roller R4, the stop member 123 is stopped at the first stop position P1. Hereafter, in order to make the word “the leading end in the conveying-out direction” distinguishable from the word “the leading end in the conveying-in direction”, “the leading end in the conveying-out direction” is expressed as “the inversed leading end in the conveying-out direction” or “the inversed leading end”.
Here, the first stop position P1 is a position to stop the stop member when the inversed leading end of the preceding sheet has passed over the lower end position of a conveyance path switching member G1 and reached a region before a nip section of a conveying-out drive roller R4, whereby the interruption of a succeeding sheet can be avoided.
After the stop member 123 conveying the preceding sheet S1 has stopped at the first stop position P1, a succeeding sheet S2 is conveyed in towards the sheet storage section 12 by the rotation of the conveying-in drive roller R3. Since the inversed leading end of the preceding sheet S1 is positioned upward from the leading end of the succeeding sheet S2 by shifting the stop member 123 to the first stop position P1, the inversed leading end of the preceding sheet S1 does not interfere with the leading end of the succeeding sheet S2.
Then, with the conveying-in of the succeeding sheet S2 into the sheet storage section 12, the stop member 123 is driven by the stop member shifting section, and returns to the initial stop position P0, and the preceding sheet S1 and the succeeding sheet are stored on the stacked condition in the sheet storage section 12.
When the predetermined number of sheets S are stored in the sheet storage section 12, the stop member 123 is driven again by the stop member shifting section so as to be shifted upward, and is stopped at the second stop position P2 located at the downstream side of the first stop position P1 in the sheet conveying-out direction.
Here, the second stop position P2 is a position to stop the stop member 124 when the reversed leading end of the plural sheets S shifted together with the stop member 123 arrives at a position where the reversed leading end of the plural sheets S come in contact with the lengthwise aligning member 124 in such a way that the plural sheets S are aligned in the sheet conveying direction.
The conveyance path switching member G1 is arranged at the upper portion of the sheet storage section 12 and switches a conveying-in path to convey a sheet S into the sheet storage section 12 and a conveying-out path to covey a sheet S from the sheet storage section 12.
The plural sheets S aligned by the lengthwise aligning member 124 are pinched between the conveying-out drive roller R4 and the conveying-out follower roller R11 by the switch operation of the conveyance path switching member G1, and are conveyed to the sheet conveying-out section 13.
The sheet conveying-out section 13 is equipped with a sheet conveying path r13 including an intermediate conveying roller R5, a sheet ejecting roller R6, and a guide plate 131. In the sheet conveying-out section 13, the plural sheets S stored in the sheet storage section 12 are conveyed out inversely on the stacked condition, and are conveyed into a succeeding sheet post processing apparatus FS.
Further, the sheet inversing section 14 is equipped with a sheet conveying path r14 including conveying rollers R7 and R8, and a guide plate 141. In the sheet inversing section 14, the plural sheets S stored in the sheet storage section 12 pass over an upper sheet conveying path r15, are re-inversed by a switchback operation on a sheet conveying path r14, pass over a lower sheet conveying path r16, are discharged from the lower sheet conveying path r16, and are sent into the succeeding sheet post processing apparatus FS.
A conveyance path switching member G2 arranged at the sheet conveying-out section 13 switches a path either one of the sheet conveying path r13 to convey the plural sheets S conveyed from the sheet storage section 12 to the conveying-out drive roller R4 along the guide plate 131 and the sheet conveying path r15 to convey the plural sheet S to the sheet inversing section 14.
A conveyance path switching member G3 arranged at the lower part of the sheet inversing section 14 switches a path either one of the sheet conveying path r15 being opened by the conveyance path switching member G2 and the sheet conveying path r16 to discharge the plural sheets S from the sheet inversing section 14. The conveyance path switching members G1, G2, and G3 are connected with solenoids respectively and are driven by them.
According to the intermediate conveyance unit B described in the above publication, even when preceding sheets are subjected to a post processing, it is possible to stack plural succeeding sheets without making them to interfere with each other and to conduct a lengthwise aligning process at high speed, without stopping conveyance of the plural succeeding sheets.
Moreover, since the stop member 123 constituting the sheet storage section 12 to store the preceding sheets S1 is shifted to the first stop position P1 before the leading end of the succeeding sheet S2 advances into the sheet storage conveyance path r12, the leading end of the succeeding sheet S2 does not interfere with the inversed leading end of the preceding sheet S1, and the succeeding sheet S2 is stacked properly on the preceding sheet S1.
However, in the intermediate conveyance unit B described in the above publication, since the shifting of the stop member 123 from the initial stop position P0 to the first stop position P1 is performed at high speed, even if the stop member 123 is stopped at the first stop position P1, the sheet S1 may proceed excessively according to the inertia of the sheet S1. That is, when the stop member 123 is stopped at the first stop position P1, if the leading end (inversed back end) of the sheet S1 is in close contact with the contact surface of the stop member 123, the back end (the inversed leading end) may locate between the conveying-in drive roller R3 and the conveying-out drive roller R4. However, the leading end separates away from the contact surface of the stop member 123 according to the inertia of the sheet S1. As a result, the inversed leading end of the sheet S1 is pinched between the conveying-out follower roller R11 of the conveyance path switching member G1 and the conveying-out drive roller R4, and there is fear to cause a problem that the sheet S1 is left on the pinched condition even if the stop member 123 is shifted downward to the initial position P0. An occurrence of the phenomenon that the sheet to be shifted downward does not come down without following the stop member 123 being shifted causes problems, such as a conveyance failure of a sheet, and an aligning failure, and further causes a big problem.